1. Field of the Invention
The present invention is directed to blast resistant prefabricated wall units and to the use thereof to construct building structures.
2. Background Art
Blast resistant structures in prior times were generally limited to defense installations where blasts from exploding ammunition dumps, missile lift-off failures, or the threat of enemy action reinstated consideration of such structures. Recently, however, the threat of suicide bombers, car bombs, and the like, have raised the threshold of consciousness relative to the desirability of such structures generally, in particular for desirable terrorist targets such as tall office buildings, government buildings, embassies, and the like, worldwide.
Occupants of buildings subjected to explosive blasts risk the possibility of death or injury not only by the blast itself and primary projectiles set in motion by the blast, but also by “secondary” projectiles which are originally part of the structure walls, and which are detached from the walls and accelerated inwards by the external shock wave. Thus, for example, in the case of prefabricated wall units of layers of sheetrock, masonry board or the like, conventionally fabricated with studs, sole plates, and top plates, a blast easily fragments the exterior and interior boards as the walls bend inward from the blast. The fragments become large projectiles, in many cases exceeding the destructive capacity of projectiles from the blast itself.
In U.S. Pat. No. 6,119,422, a panel construction is disclosed where wall layers such as gypsum board are bonded together with an adhesively bonded web mesh, in order to withstand impacts resulting from high winds such as those caused by tropical storms and hurricanes. However, such panels are unlikely to survive impacts from primary projectiles or the shock waves created by explosive events, and in any case, will still generate secondary projectiles in the case of the latter. No prefabricated walls are disclosed.
U.S. Pat. No. 4,242,406 discloses panels which are designed to be structural, i.e. to bear significant load, comprising a plastic surface finish adhered to a reinforcing layer prepared from an organic casting resin and containing reinforcing fibers, an intermediate bonding layer containing chopped glass fibers, and fiberglass-reinforced gypsum board as the final layer. While the panels are designed to be structural, they are not designed to resist impact. Moreover, prefabricated wall structures are not disclosed.
It would be desirable to provide blast resistant prefabricated wall units which do not fragment into secondary projectiles in the case of a blast. It would be further desirable to provide a building structure which can absorb considerable blast energy.